Chemicals, plastics and rubber industries

Theoretical study on the topochemical nature in the initiation process of the solid-state thermal isomerization reaction of methyl 4-(dimethylamino)benzenesulfonate

Article Abstract:

Ab initio molecular orbital experiments were conducted to investigate the initiation reaction of the methyl 4-(dimethylamino)benzenesulfonate (MDBS) thermal isomerization to N,N,N,-trimethylbenzenaminium-4-sulfonate (TBS) in the crystalline state. Aside from the topochemical nature of the initiation reaction, the ionic intermediates and crystal structures of MDBS and TBS were compared. The arrangement of a pair of molecules in the MDBS crystal optimized the transition-state structure. Moreover, in-phase molecular rotation in the MDBS induced the initiation stage of thermal isomerization.

A rapid reversible solid-state transition in the A' form of pentadecanoic acid

Article Abstract:

A study was conducted to analyze a rapid reversible solid-state transition in the A'form of pentadecanoic acid. The acid samples were made using a combination of urea adducts, acid soap and fractional distillation techniques. A stereomicroscope was then utilized to examine single-crystal specimens. Experimental results indicated that the energy barriers among polymorphs supported the conversion transition of B' to A in two steps.